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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
/*
pYIN - A fundamental frequency estimator for monophonic audio
Centre for Digital Music, Queen Mary, University of London.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version. See the file
COPYING included with this distribution for more information.
*/
#ifndef _MEAN_FILTER_H_
#define _MEAN_FILTER_H_
class MeanFilter
{
public:
/**
* Construct a non-causal mean filter with filter length flen,
* that replaces each sample N with the mean of samples
* [N-floor(F/2) .. N+floor(F/2)] where F is the filter length.
* Only odd F are supported.
*/
MeanFilter(int flen) : m_flen(flen) { }
~MeanFilter() { }
/**
* Filter the n samples in "in" and place the results in "out"
*/
void filter(const double *in, double *out, const int n) {
filterSubsequence(in, out, n, n, 0);
}
/**
* Filter the n samples starting at the given offset in the
* m-element array "in" and place the results in the n-element
* array "out"
*/
void filterSubsequence(const double *in, double *out,
const int m, const int n,
const int offset) {
int half = m_flen/2;
for (int i = 0; i < n; ++i) {
double v = 0;
int n = 0;
for (int j = -half; j <= half; ++j) {
int ix = i + j + offset;
if (ix >= 0 && ix < m) {
v += in[ix];
++n;
}
}
out[i] = v / n;
}
}
private:
int m_flen;
};
#endif
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